Diodes are often desired to have low losses and also a sufficient dynamic robustness and high robustness against cosmic radiation, respectively. For dynamic reasons, in particular to ensure low switching losses and low reverse current peaks, a low efficiency of an anode emitter of the diode, i.e. a low doping of the anode region, is often required to reduce flooding of an adjoining weakly doped semiconductor region with charge carriers. During fast commutating the diode, i.e. during fast switching off or switching the diode from forward to reverse current direction, and/or due to cosmic radiation a high density current of holes may flow towards the anode region. The positive charge of the holes may at least partially compensate the doping charge of the anode region. Accordingly, the space charge region may extend deep into the anode region. In case the space charge region reaches an anode metallization in electric contact with the anode region, a breakdown may occur which in consequence may lead to the destruction of the diode. Highly and/or deeply doped anode regions are often desired to avoid breakdown of diodes. However, highly and/or deeply doped anode regions tend to increase switching losses and reverse current peaks. Furthermore, other known measures to reduce switching losses and reverse current peaks of diodes are often accompanied by undesired side effects. For example, the charge carrier life time in the anode region and/or in the semiconductor material below the anode region may be reduced by irradiation or ion implantation using protons, helium, or argon, for example. However, an increased reverse current, which is particularly unfavorable for high voltage diodes, is observed in this case.
Accordingly, there is a need to provide a diode with improved trade-off between dynamic properties and robustness during fast commutation and against cosmic radiation, respectively.